The invention relates to a plate link chain for infinitely adjustable cone pulley drives, the link pivot elements of which, joining the individual chain links embodied by plate link packets, are embodied as thrust members, which are inserted into recesses of the plate-links and with their end faces serve to transfer frictional force between friction wheels and the plate-link chain.
Chains of this type have a great variety of embodiments in terms of the link pivot elements, with respect to which reference can be made merely by way of example to German Pat. Nos. 1 302 795, 2 356 289, 2 848 167, 3 027 834 and 3 129 631. The link pivot elements may be cylindrical link pins, pairs of link pivot elements in the same recess, or the like.
In all the plate-link chains of the type in question, there are impacts, hence producing undesirable structure-borne sound, between the thrust members and the friction wheels when the chain enters the wedge of a pair of friction wheels. These noises are particularly disagreeable whenever the periodic impacts enter the range of resonant vibrations of parts of the drive mechanism, such as the friction wheels and the housing walls, and they are subjectively perceived as particularly annoying when they are heard as a piercing single tone, possibly along with its harmonic.
An attempt has been made to address this problem by reducing the chain graduation and hence lessening the spacing between adjoining link pivot elements, so as to increase the frequency of pulses and decrease their intensity. Another attempt that was made involved impeding the uniformity of the single-tone production by providing for a non-uniform chain graduation, which also aided in hindering the buildup of vibrations.
Although these provisions were quite successful, still it has been realized that there is a need for further improvement in terms of noise reduction, because for other reasons, such as structurally dictated chain lengths, it has not been possible to fully exploit these provisions.